Apparatus for disassembling wooden pallets

ABSTRACT

Apparatus for the disassembly of wooden pallets or the like is disclosed. Generally, a pallet comprises a nailed together wood structure having a plurality of parallel, spaced stringers and a plurality of slats nailed to the top and bottom faces of the stringers and extending generally transversely thereof. The apparatus of this invention comprises a frame, a table mounted on the frame for receiving a pallet to be disassembled, and a plurality of cutters, one for a respective stringer, for cutting the nails holding the slats to a respective stringer. The table with the pallet thereon is movable from a retracted position in which the pallet is clear of the nail cutters to an operative position. A pallet clamp is provided on the table for holding the pallet in position with its stringers extending parallel to the direction of movement of the table. The nail cutters are adjustably movable in transverse direction so that at least certain of the nail cutters may be aligned with respective stringers.

BACKGROUND OF THE INVENTION

This invention relates to apparatus for and method of disassembling (orpartially disassembling) nailed together wooden structures, such aswooden pallets or the like.

Generally, wood pallets are used in many industries for the handling ofvarious goods or materials. A pallet typically is a platform on whichgoods are stacked or otherwise supported with the pallet serving as astacking platform or support so as to facilitate the handling of theentire load of goods stacked on the pallet by means of a forklift. Awood pallet generally consists of a plurality of spaced wood stringermembers exending generally in parallel direction. Oftentimes thestringer members are made of 2×4 lumber and are stood on edge so thattheir widest sides extend vertically. A number of wooden slats made, forexample, of 1×4 lumber or the like, are placed transversely across thestringers and are nailed to the upper and lower faces of the stringers.The pallets may be rectangular or square (when viewed in plan) and mayhave slats nailed to the top and bottom faces of the stringers or onlyto the top of the stringer members. It will be appreciated that with thepallet resting on the floor and with the load supported on the upperslats, the lifting tines of a forklift may be readily inserted into thepallet between the stringers below the top slats so as to facilitatelifting of the pallet together with its load.

In use, pallets oftentimes become damaged thus necessitating theirrepair or disposal. In order to economically repair pallets, it isnecessary that the damaged wood members be readily removed and replaced.It is especially difficult to remove a stringer because all of the slatsnailed thereto must be removed. To this end, apparatus, such as is shownin U.S. Pat. No. 3,869,780, has become available in the pallet industry.In general, the apparatus shown in the above-noted patent operates bymoving a pallet to be repaired past a stationary nail cutter (e.g., apair of overlapping rotary cutting wheels) carried on a buck orcantilevered support so as to shear the nails holding the slats to oneedge of a respective stringer. By turning the pallet over, by aligningthe same stringer with the nail cutter, and by repeating the nailcutting operation, all of the nails holding a stringer in place withinthe pallet may be cut thus permitting the removal of the stringer. U.S.Pat. No. 4,152,819 discloses an improvement of the apparatus shown inthe above-noted '780 patent in which the circular knife blades areparticularly well-suited to cut hardened, machine driven nails. However,while the above apparatus did represent an improvement over prior palletrepair techniques, the apparatus of the '780 patent was relatively slowas it took ten or more seconds to cut the nails on each side of eachstringer, and the apparatus of both prior patents required that thepallet be turned over and repositioned so as to cut the nails holdingthe slats to both faces of a stringer.

In recent years, the cost of the lumber required to construct a pallethas steadily increased. Pallet refurbishing operators have known forsome time that lumber from damaged pallets can be used in theconstruction or repair of other pallets. Heretofore, however, it oftenwas not feasible to manually disassemble damaged pallets for the purposeof salvaging lumber therefrom due to the labor costs involved inproperly disassembling a pallet.

Reference may also be made to such prior U.S. Pat. Nos. as 2,593,843,3,512,242 and 3,740,815 which disclose various prior palletdisassembling apparatus. In general, these prior apparatus function bypulling the slats from the stringer so as to disassemble the pallet.However, it will be appreciated that with the slats pulled from thestringers, that sharp nails extend from the slats and must be removedthus resulting in further labor costs and presenting a significanthazard to personnel handling the disassembled lumber.

The apparatus shown in the above-noted U.S. Pat. No. 3,869,780 has beenused in the total disassembly or stripping of pallets. However, therelatively slow operating speed of the apparatus and the necessity formultiple repositioning the pallet relative to the nail cutting bladesresults in high labor costs for totally disassembling pallets thuseliminating, at least in part, some of the advantages gained bydisassembling damaged pallets for the purpose of reclaiming lumber.

Among the several objects and features of this invention may be notedthe provision of apparatus for and method of disassembling woodenpallets in an efficient and economical manor substantially withoutcausing damage to the wooden members;

The provision of such apparatus which permits a pallet to bedisassembled to be readily placed in the apparatus and which requires aminimum of repositioning of the pallet during operation of theapparatus;

The provision of such apparatus which may be readily adjusted toaccomodate pallets of various configurations and sizes;

The provision of such apparatus in which certain of the nail cuttingmeans are self-aligned with the nails in a respective stringer uponcutting the nails once the nail cutters have been generally aligned withthe respective stringers so as to effect nail cutting substantiallywithout damage to or interference from the wood members of the pallet;

The provision of such an apparatus which aids workmen by automaticallyseparating the stringers from the slats and by automatically removingwood members from the apparatus;

The provision of such apparatus which is of rugged construction andwhich is reliable in operation;

The provision of such apparatus and method which enables the slats to becut loose from the top and bottom of the stringers without repositioningor turning the pallet; and

The provision of such apparatus and method which requires minimum amountof labor and time to use.

Other objects and features of this invention will be in part apparentand in part pointed out hereinafter.

SUMMARY OF THE INVENTION

Briefly stated, apparatus of this invention is provided for thedisassembly of wooden pallets or the like, these pallets comprisingnailed together wood structures having a plurality of spaced stringersextending parallel to one another and a plurality of slats nailed to thestringers and extending generally transversely of the stringers. Theapparatus comprises a frame, a table mounted on the frame for receivinga pallet to be disassembled, a plurality of nail cutting means, one fora respective stringer, for cutting the nails holding the slats to arespective stringer, and means for moving the table with the palletthereon from a retracted position in which the pallet is clear of thenail cutting means and an operative position. Additionally, means isprovided for clamping the pallet on the table in position with itsstringers extending parallel to the direction of movement of the table.Other means is provided for adjustably moving at least some of the nailcutting means transversely relative to the pallet clamped on the tableso as to align the nail cutting means with respective stringers.

The method of this invention involves moving a pallet from a loading ora retracted position to a cutting position, the pallet being moved inthe longitudinal direction of its stringers as it is moved between itsloading and cutting positions. A pair of shear blades is positioned onopposite sides of a stringer at an interface of the stringer and theslats nailed thereto. Then, the shear blades are actuated so as tosubstantially simultaneously shear all of the nails holding the slats tothe above-said stringer at the stated interface so as to free all of theslats from this one stringer. Then, a pair of shear blades is positionedon opposite sides of this one stringer and the other slats nailedthereto. This last-mentioned pair of shear blades is actuated so as tosimultaneously shear all of the other slats nailed to this one stringer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of apparatus of the present invention fordisassembling a wood pallet or other wood structure illustrating inphantom a wood pallet held in place on a table in its retracted positionwith the various stringers of the wooden pallet aligned generally withrespective nail cutting means;

FIG. 2 is an enlarged side elevational view taken along line 2--2 ofFIG. 1 illustrating the left hand portion of the apparatus with partsbroken away to show internal details;

FIG. 3 is a view similar to FIG. 2 illustrating a parallelogram linkageand hydraulic cylinder arrangement for raising and lowering the table onwhich a pallet to be disassembled is clamped;

FIG. 4 is an enlarged side elevational view of the right hand portion ofthe apparatus taken along line 4--4 of FIG. 1 illustrating a wheeledtrolley arrangement and power actuated system for adjustably movingcertain of the nail cutting means in generally transverse direction ofthe pallet being disassembled thereby to enable the nail cutting meansto be aligned with respective stringers of the pallet;

FIG. 5 is a vertical cross sectional view taken along line 5--5 of FIG.4 illustrating further details of the system for adjustably movingcertain of the nail cutting means relative to their respectivestringers;

FIG. 6 is an enlarged plan view of one of the nail cutting means, asshown in FIGS. 1-5;

FIG. 7 is a front end elevational view of the nail cutting means shownin FIG. 6 together with a respective stringer and slat member of atypical pallet;

FIG. 8 is an enlarged cross sectional view of one of the nailing cutterstaken along line 8--8 of FIG. 7;

FIG. 9 is a bottom view of the outer end of one of the arms supportingthe nail cutting means shown in FIG. 6 and further illustrating meansfor adjusting the nailing cutting blades relative to one another and forlocking the blades in a desired position relative to one another;

FIG. 10 is a plan view of another embodiment of a nail cutting means ofthe present invention having a pair of opposed shear blades movablerelative to one another for severing or shearing the nails holding theslats to a respective stringer;

FIG. 11 is a cross sectional view of this second nail cutting meanstaken along line 11--11 of FIG. 10 illustrating an upper blade forcutting the nails holding the upper slats to a respective stringer and,upon repositioning of the blade assembly relative to the stringer,having a lower blade for cutting the nails holding the bottom slats tothe stringer thereby to effect cutting of both the top and bottom nailswithout repositioning or turning of the wood pallet on the apparatus;

FIG. 12 is a view similar to FIG. 11 depicting the lower bottom blade inits actuated position for cutting the nails adjoining the slats to thebottom of the stringer;

FIGS. 13a-13c are plan views of still another embodiment of nail cuttingmeans of the present invention utilizing shear blades for cutting thenails, these views depicting various stages of the shearing action ofthis nail cutting means;

FIG. 14 is a vertical cross sectional view taken along line 14--14 ofFIG. 13a;

FIG. 15 is an enlarged side elevational view taken along line 15--15 ofFIG. 13c; and

FIG. 16 (sheet 2) is an enlarged view of a portion of the pallet supporttable illustrating a spring supported pallet abutment member.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings, apparatus of this invention is indicatedin its entirety at reference character 1 and it is shown to comprise aframe 3 including rail members 5 extending longitudinally of the frame.As is generally indicated at 7, a table is rollingly mounted on railmembers 5 for movement therealong in generally longitudinal direction ofthe apparatus. A plurality of nail cutting means, as generally indicatedat 9A, 9B and 9C, is supported at the other end of frame 3. As indicatedgenerally at P, a wooden pallet to be disassembled is positioned andsupported on table 7. As is typical, pallet P includes a plurality ofparallel stringers 10 spaced apart from one another. As shown in FIG. 1,pallet P includes three parallel stringer members equally spaced fromone another and extending in generally longitudinal direction of thepallet. It will be understood however, that pallets having a number ofstringers other than three may readily be used in conjunction with theapparatus of the present invention. As is conventional, a plurality ofwooden slats 11 are spaced from one another and extend generallytransversely of the stringers and are nailed to the upper and lowerfaces of the stringer by nails N (see FIG. 11).

Table 7 comprises a platform 13 mounted on a carriage 15 by means of aparallelogram linkage arrangement 17 (see FIG. 3). Carriage 15 ismounted on rollers 19 which are engageable with rail members 5 forrollingly supporting the carriage and the platform on the frame asheretofore described. A hydraulic cylinder unit 21 (see FIG. 3) isinterposed between carriage 15 and platform 13 for selectively raisingand lowering the platform on parallel linkage arrangement 17 relative tothe carriage or relative to nail cutting means 9A, 9B or 19C. Of course,parallelogram linkage 17 maintains the platform in generally horizontalposition as it is raised and lowered.

Platform 13 has an upper surface which supports pallet P to bedisassembled. The platform includes a stationary front abutment member23 which extends generally transversely across the platform and which isintended to engage the lower leading edge of a pallet P placed on theplatform. The latter is provided with a movable clamp member 25 carriedby spaced slide members 27a, 27b. Clamp member 25 is movable between anopen position (as shown in FIG. 3) and a closed or clamping position(see FIG. 2). The clamp member is moved between its open and clampingposition by means of a hydraulic cylinder unit 29 interposed between theplatform and the clamp member. The clamp member further has a rearabutment member 31 extending transversely of the platform which isengageable with the lower trailing edge of the pallet. Further, platform13 is provided with a pair of endless conveyor chains 32 entrainedaround sprockets 33 provided at the ends of the platform. These chainshave dogs D which extend outwardly therefrom and which protrude abovethe upper surface of platform 13 for engaging wood members (e.g.,stringers 10) remaining on the platform after disassembly of the palletand for conveying these loose wood members to one side of the platform.It will be understood that the chains may be driven through a cycle toremove the loose wood members from the platform by actuating a hydraulicmotor (not shown) for at least a partial cycle of the chains aroundtheir respective sprockets 33.

As generally indicated at 34 in FIG. 2, a hydraulic powered winch andcable assembly is provided in apparatus 1 for forceably moving table 7relative to frame 5 between a retracted or loading position (as shown inFIGS. 1-3) in which a pallet P may be loaded on and clamped in place onplatform 13 such that the pallet is clear of nail cutting means 9A, 9Band 9C and an operative position in which the stringers are in positionto be operated on by the nail cutting means. Winch arrangement 34includes a hydraulic motor 35 which powers a winch 37 in both forwardand reverse directions. As shown in FIG. 4, a pulley 39 is journalled onframe 3 distal from the retracted position of table 7. A cable 41 iswound up on one side of winch 37, is trained around pulley 39, and isthen wound up on the other side of the winch. Carriage 15 is securelyfastened to the upper reach of cable 41 between winch 37 and pulley 39by means of an attachment clamp 43 (see FIG. 2). Upon operation of winch37 in one direction, cable 41 is unwound from one side of the winch andis wound up on the other side of the winch causing generally horizontalmovement of the upper reach of the cable which in turn causes thecarriage connection 43 to move or reciprocate in horizontal directionfrom its position shown in FIG. 2 toward pulley 39 thereby to effectmovement of table 7 from its retracted position toward its operativeposition. Of course, upon reverse energization of winch 37, table 7 iscaused to move toward its retracted position. It will be understood thattable 7 may be stopped at any position along its path and that hydraulicmotor 31 drives the table along its path at considerable speed. Forexample, it may take only one or two seconds for the table to make afull trip from its retracted position to its full operative position atwhich point attachment 43 is proximate pulley 39. Of course, the returnstroke of the table may be carried out with comparable speed. It will beunderstood that limit switches (not shown) along the path of table 7 maybe operated to terminate travel of the table at any direction at adesired location along the path of the table in a manner well known tothose skilled in the art.

Nail cutting means 9A, 9B and 9C each includes a pair of elongate,cantilevered support arms 45a, 45b. These arms are spaced from oneanother a distance sufficient to accomodate a stringer 10 of pallet Ptherebetween (see FIG. 7). The support arms of the center nail cuttingmeans 9C are fixedly mounted on frame 3 so as to be generally in linewith the longitudinal centerline of apparatus 1. However, in accordancewith this invention, the outer nail cutters 9A and 9B are independentlyand selectively movable in generally horizontal transverse direction (asshown by the arrows in FIG. 1) relative to the frame so as to enablethese outer nail cutters to be aligned with their respective stringers10 on pallet P which is held in position on table 7 for disassembly.While the arms 45a, 45b of center nail cutting means 9C were hereabovedescribed as being in fixed position, it will be understood that, withinthe broader aspects of this invention, the center nail cutting means 9Cmay also be adjustable in transverse position.

More specifically, support arms 45a, 45b for each of the outer nailcutters 9A, 9B are mounted on a respective carriage or trolley 47A, 47Bwhich is movable on rails or tracks 49 secured to frame 3. Specifically,these carriages are movable in transverse direction relative to frame 3.As shown in FIG. 4, tracks 49 face one another and are spaced apartapproximately the width of trolleys 47A, 47B. The latter each includesrollers 51 disposed on the top or bottom of each of the tracks 49 so asto rollingly support the trolley for transverse movement relative to theframe and for rigidly holding the arms 45a, 45b cantilevered from thetrolley in generally horizontal position.

Each trolley 47A or 47B for outer nail cutters 9A, 9B is selectivelymoved in transverse direction by means of a respective hydrauliccylinder unit as indicated at 53A, 53B (see FIGS. 4 and 5). Thesehydraulic units are interposed between frame 3 and their respectivetrolleys. Each of these cylinder units has a stroke of sufficient lengthso as to transversely move its respective nail cutter 9A or 9B from aninner position adjacent (i.e., contiguous) to the fixed center nailcutting means 9C to an outer position in which the trolleys is inpositive engagement with a stop 54 on frame 5. It will be appreciatedthat when a pallet P is placed on table 7, the pallet is positioned sothat at least one stringer 9 (i.e., the center stringer) is generally inline with the fixed center nail cutter 9C. The other nail cutters 9A and9B may then be respectively aligned with their respective stringers byselectively actuating cylinder units 53A and 53B so as to move the othernail cutters 9A and 9B into alignment with their respective stringers.

In accordance with this invention, once nail cutters 9A and 9B have beengenerally aligned with their respective stringers 10 (i.e., when thecenterline between arms 45a, 45b of each nail cutter assembly isgenerally in the vertical plane of its respective stringer and in linewith the nails N to be cut thereby), hydraulic cylinder units 53A and53B are opened (i.e., pressure is relieved therefrom) so that the pistonand actuator rod of the hydraulic cylinder units are free to be moved inand out of their hydraulic cylinders upon application of axial force inone direction or the other to their actuator rod. As the nail cutterbegins to cut nails, a reaction force is, of course, applied to arms45a, 45b if the nail cutter is not properly positioned on its respectivestringer. In turn, a transverse force will be applied thereto whichtends to transversely shift its respective trolley 47A or 47B on tracks49 thereby to effect the automatic self-centering or self-aligning ofthe nail cutter with regard to its respective stringer 10. Thus, it willbe appreciated that with cylinder units 53A or 53B open, these cylinderunits in combination with their respective trolleys 47A, 47B constitutemeans for enabling the self-centering or self-alignment of the nailcutters with their respective stringers upon effecting cutting of nailsN.

Referring now to FIGS. 6-8, a first embodiment of nail cutters 9A, 9Band 9C is therein shown. As illustrated, the nail cutters each comprisea pair of circular cutting blades 55a, 55b carried on the outer or freeends of a respective pair of cantilever arm 45a, 45b. As shown in FIG.6, a portion of each of these circular blades overlap one another alongthe longitudinal centerline of the space or gap between arms 45a, 45band thus are in general sliding, shearing relation in the area ofoverlap. Each of the blades is rotatably mounted on its respective arm45a or 45b by means of an anit-friction bearing 57 (e.g., a ball orroller bearing) in such manner as to be free to rotate about a generallyvertical axis and in such manner as to be positively held in place onits respective arm and to be undisturbed by the cutting of nails N inthe manner as will appear.

In FIG. 8, a blade 55a is shown to be mounted on its arm 45a by means ofa stud 59 which in turn is secured to a plate 60. A nut 61 holds stud 59on plate 60 and the latter is positively secured to the outer end of itsrespective cantilever arm 45a, 45b in a manner as will be hereinafterdescribed. Bearing 57 includes a inner race 63 and an outer race 65 withroller element 67 disposed therebetween. A sleeve 68 is fitted withininner race 63 of the bearing and stud 59 is received within the sleeveand is bolted in place on its respective arm 45a or 45b. Outer race 65of the bearing is pressed into a bore 69 of a mounting member 71 so thatthe mounting member is rotatably supported by the bearing. As indicatedat 73, cap screws are countersunk into the center portion of blade 55aand are threaded into mounting member 71 so that the blade is positivelysecured to and is rotatable with the mounting member. In this manner,rotary cutting blades 55a and 55b are securely fastened to theirrespective arms 45a, 45b and are thus securly held thereon while cuttingnails N.

Further in accordance with this invention, blades 55a, 55b may beselectively adjusted relative to one another for the purpose of varyingthe amount of overlap of the cooperating circular blades. As generallyindicated at 75 in FIG. 9, means is provided for selectively adjustingthe relative positions of the blades relative to one another andrelative to their respective arms 45a, 45b and for securely andpositively locking the blades in a desired position. As described above,circular blades 55a, 55b are secured to their respective end plates 60by means of mounting member 71 and bearing 57. The outer end of endplate 60 is preferably pointed, as indicated at 76, so as to guiderespective stringers 10 into proper cutting relation with the blades.Means 75 is shown to comprise a pivot bolt 77 located adjacent the outerend of its respective arm 45a or 45b, and a slotted bolt connection 79between plate 60 and its respective arm 45a or 45b and a cam lock bolt81 (see FIG. 6). As shown in FIG. 9, plate 60 is cut out, as indicatedat 83, so as to receive an eccentric locking cam 85 carried by cam lockbolt 81. It will be appreciated that by loosening bolts 77, 79 and 81,plate 60 may be pivotted at about pivot bolt 77 to any desired angularposition relative to its respective arm 45a or 45b. With the plate inits desired angular position with respect to its arm, cam 85 may bebrought into firm engagement with cam surface 83 on plate 60. Upontightening of cam lock bolt 81, the cam of course will be firmly lockedin place against plate 60 and it will positively prevent rotation of theplate in at least one direction. Of course, bolts 77 and 79 may also betightened to more securely hold plate 60 in is desired angular positionwith respect to its respective arm 45a or 45b.

Again referring to FIG. 6, a plate 87 is welded or otherwise rigidlysecured between the upper faces of arms 45a, 45b adjacent cutting wheels55a, 55b. Preferably, plate 87 is of spring steel or the like so as toresiliently link arms 45a, 45b together and so as to permit at leastsome degree of resilient relative movement between the arms. Further,the upper surface of plate 87 is disposed approximately at the level ofcutting knives 55a, 55b for aiding in handling slats 11 after they havebeen disassembled from pallet P.

The various hydraulic cylinder units and hydraulic motors heretoforedescribed in apparatus 1 may, of course, be supplied with hydraulicfluid under pressure from any suitable source. For example, any one of anumber of well-known and commercially available hydraulic motor and pumpsets (not shown) may be utilized. Furthermore, each of the hydrauliccomponents of apparatus 1 may readily be controlled from an operatorsconsole 89 provided at one end (the left end of the apparatus as viewedin FIG. 1). It will be appreciated that operator console 89 may includevarious control valves, such as a Model CM2N02R25DOCDDBL30 control valvecommercially available from the Vickers Company, Division of Sperry RandCompany of Troy, Mich. These valves may be selectively operated so as tocontrol operation of table lift cylinder 21, clamp cylinder 29, winchmotor 35, nail cutter cylinders 53a, 53b, and the hydraulic motorpowering chain conveyors 32. Furthermore, hydraulic lines for supplyinghydraulic fluid to hydraulic cylinders 21 and 29 and to the motor fordriving chain conveyors 32 on table 7 are supported by an articulatedhose support 91 (see FIGS. 2 and 4) which is pivotally attached to frame3 and to table 7 and which has a pivoted knee 93. In this manner, thevarious hydraulic lines for supplying hydraulic fluid to the hydrauliccomponents of table 7 are supported above the level of nail cuttingmeans 9A, 9B and 9C and are maintained clear of all other structure ofapparatus 1 during operation of the machine and during movement of table7 between its retracted and operative positions.

In operation, a pallet P is moved into a desired position on platform 13of table 7 and is oriented with its stringers 10 extending generallyparallel to the direction of movement of table 7 on frame 3. The palletP shown in FIG. 1 has three stringers 10 so that all of the upper slats11 of the pallet may be disassembled from one face (i.e., the upperface) of stringers 10 upon one pass of table 7 relative to nail cutters9A, 9B and 9C. It will be understood, however, that pallets having othernumbers of stringers 10 may be readily disassembled by means ofapparatus 1 of the present invention.

With pallet P positioned on platform 13, the center stringer of thepallet is aligned with the center, or fixed position nail cutter 9C.Then, hydraulic cylinder units 53A, 53B are selectively energized so asto shift trolleys 47A and 47B in transverse direction with respect toframe 3 so as to align their respective nail cutters 9A, 9B with respectto other stringers of pallet P. Then, hydraulic cylinder unit 29 isactuated so as to move clamp member 25 into firm clamping engagementwith the trailing edge of the pallet and so as to firmly hold the palletin place between front abutment member 23 and rear abutment member 31.Then, hydraulic cylinder unit 21 is selectively energized to raise orlower platform 13 relative to the nail cutters so that the interfacebetween the upper slats 11 and the upper face of stringers 10 of palletP are generally in the horizontal plane of blades 55a, 55b of the nailcutters. Motor 35 is then energized with hydraulic fluid under pressureso as to cause operation of winch 37 in such direction to forceablyshift the upper reach of cable 41 and attachment 43 to move to the right(as shown in FIG. 2) thereby to in turn cause table 7 to move from itsretracted or loading position toward its operative position. As theforward or leading ends of stringers 10 encounter their respective nailcutting knives 55a, 55b, the edges of the knives are forced, by movementof table 7 with the pallet P clamped, between the interface of thestringers 10 and the upper slats 11. As the knives engage nails Nholding the upper slats in place, the nails are sheared by the knivesthereby disassembling the upper slats from the stringers. Of course, ona three stringer pallet, all of the upper slats are disassembled fromtheir respective stringers by the three nail cutting means upon onecycle of table 7 from its retracted to operative position. As the slatsare disassembled from their respective stringers, they pile up on theupper surfaces of arms 45a, 45b and are supported thereby. As otherpallets are disassembled, the slats will accumulate on the upper surfaceof arms 45a, and 45b. Of course, workmen may manually remove thedisassembled slats or they may be automatically fed directly from therear end of apparatus 1 of this invention into suitable automatic sawingequipment (not shown) for cutting the newly disassembled lumber intousable sizes.

Further in accordance with this invention, it will be appreciated thattable 7 is moved relatively rapidly from its retracted position to itsoperative position thereby to effect the cutting of nails N and toreturn to its retracted position. For example, by using motor 35 andwinch 37 to move table 7, the table may be moved through a full cycle ina matter of a few seconds (e.g., 2-4 seconds) thereby to simultaneouslydisassemble all of the upper slats from the stringers. By moving thetable in relatively high speed relative to the nailing plates, theefficient shearing of nails N is accomplished substantially withoutsplitting or damage to either the stringers or the slat members.Surprisingly, not only does the increased operating speed of theapparatus of the present invention markedly increase the production rateof the machine, but the percentage of boards damaged by the machine ofthis invention is lower than experienced in using the slower prior artapparatus.

After the upper slats 11 have been removed from pallet P, and aftertable 7 has been returned to its retracted position, clamp member 25 ismoved to its open position and the remaining portion of the pallet ismanually turned over on table 7 so that the slats that formerlyconstituted the bottom slats of the pallet face upwardly. Again, thecenter stringer of the pallet is aligned with the fixed center nailcutting means 9C and clamp member 25 is brought into firm clampingengagement with the trailing ends of the stringers thereby to firmlyhold the pallet on table 7 between abutments 23 and 31. Assuming thatthe outer stringers are each symetrically located with respect to thecenter stringer, adjustment of the outer nailing cutters 9A and 9B isusually not necessary upon turning of the pallet. Of course, it will bealso understood that if similar pallets are being disassembled, once theouter nail cutting means positioned for that type of pallet beingdisassembled, the position of the outer nail cutters will not, in mostcases, have to be adjusted until another size pallet is desired to bedisassembled. Table 7 is then reciprocated from its retracted positiontoward its operative position and the now upwardly facing slats 11 aredisassembled from their respective stringers by nail cutters 9A, 9B and9C thus cutting the nails holding the slats in place on their stringers.

Upon the return of table 7 to its retracted position and upon therelease of clamp member 25, chain conveyor 32 is energized so as toautomatically remove the stringer members 10 from table 7. It will beappreciated that upon disassembling pallets, all of the slats 11 arecollected at the rear end of apparatus 1 adjacent trolleys 7 on theupper surfaces of arms 45a and 45b and that all stringer members arecollected at the side of table 7. In this manner, the various differentwood members of the pallets are separated from one another without therequirement of a subsequent sorting operations.

Referring now to FIGS. 10-12, another embodiment of nail cutters 9A, 9Band 9C is illustrated, these other nail cutters being generallyindicated in their entirety at 101A, 101B and 101C. It will beunderstood that nail cutters 101A, 101B and 101C are supporred oncantilever arms 45a', 45b' and on trolleys 47A', 47B' in the manner ofnail cutter 9A, 9B and 9C. The primed reference characters indicateparts of similar construction and operation as parts heretoforedescribed.

Generally, these other nail cutters are identical to one another andthus only nail cutter 101A will be described in detail. Specifically,nail cutter 101A comprises a pair of reciprocable shear blade assemblies103a, 103b carried by a respective pair of spaced arms 45a', 45b'. Asshown in FIG. 11, each shear blade assembly 103a or 103b comprises aslide support member 105a, 105b secured (e.g., welded) to the inner faceof its respective support arm 45a', 45b'. At least one slide member107a, 107b is slidably mounted on its respective slide support 105a,105b for sliding in generally axial or longitudinal direction withrespect to support arms 45a', 45b'. A shear blade 109a, 109b ispreferably removably secured to the upper surface of its respectiveslide member 107a, 107b by means of countersunk bolts or screws 111. Asbest shown in FIG. 10, slide support members 105a, 105b each have anupright inclined or angled cam surface 113 cammingly engageable with arespective cam surface 115 on its respective slide member 107a, 107bthereby to effect inward movement of the slide member and its shearblade relative to its slide support member upon longitudinal movement ofthe slide member relative to its slide support. As shown in FIG. 10, camsurfaces 113 of shear blade assemblies 103a and 103b slope in oppositedirections so that upon outward longitudinal movement of slide 103atoward the free end of its respective support arm 45a', its respectiveshear blade 109a moves in toward a stringer member disposed between itsrespective support arms. On the other hand, the cam surface 113 of shearblade assembly 103b is sloped so as to effect inward movement of theshear blade upon longitudinal movement of its slide 109b away from theouter end of its respective support arm 45b'. In this manner, thesimultaneous actuation of the shear blade assemblies 103a, 103b inopposite longitudinal directions causes them to close on theirrespective stringer member and to shear nails N substantiallysimultaneously along the entire length of the stringer.

Slide members 107a, 107b are each provided with a tongue 117 (FIG. 12)which fits into a respective horizontal groove 119 in the cam surface113 of its respective slide support member 105a, 105b thereby tomaintain the slide member in desired vertical position on its slidesupport member. Of course, the slide member slidably rests on ahorizontal surface 121 of its slide support member and the slide memberand its support have suitable lubrication grease or the liketherebetween so as to permit ready sliding movement therebetween. Ofcourse, suitable retainers (not shown) may be utilized to hold blade109a, 109b in place on their respective slide support members 105a,105b.

Each shear blade assembly 103a, 103b is reciprocated in generallylongitudinal direction with respect to its support arm 45a', 45b' bymeans of a respective hydraulic cylinder unit 123a, 123b (FIG. 10)interposed between the inner end of the shear blade assembly and itsrespective support arm. These hydraulic cylinder units may of course bedouble acting cylinder units so as to forceably push and pull the shearblades relative to their support arms thereby to effect opening andclosing of the shear blades.

Referring now to FIG. 11, each shear blade assembly 103a, 103b isfurther shown to comprise an upper set of shear blades and a lower setof shear blades substantially identical to one another which areoperable independently of one another. It will further be noted in FIG.11 that the height or thickness of the shear blade assembly 103a issomewhat less than the height of stringer 10 of a typical pallet P forpurposes as will hereinafter appear.

In operation, the second embodiment of apparatus 1 of this inventionincorporating nail cutting means 101A, 101B, and 101C will hereinafterbe described. With a pallet P oriented on table 7 and clamped inposition generally as heretofore described, the table is moved from itsretracted or loading position to its operative position. As the palletmoves toward its operative position, each of the stringers 10 of thepallet is received between a pair of respective support arms 45a', 45b'.Of course, it is understood that the outer nail cutting means 101A and101B are movable in transverse direction in the manner similar to nailcutting means 9A, 9B heretofore discussed. With the pallet in its fullyoperative position, shear blade assemblies 103a, 103b of each nailcutting means 101A, 101B, 101C extend along the entire length of each ofthe stringers on opposite sides thereof. Then, cylinder unit 21 isactuated so as to adjust the height of pallet P relative to the uppershear blades by raising or lowering platform 13 so that the upper shearblade 109 of each shear blade assembly 103a, 103b is in generalalignment with the interface between the top of stringer 10 and thebottom face of the upper slats 11 (see FIG. 11). Then, upper cylinders123a, 123b of all the nailing cutters 101A, 101B and 101C aresimultaneously actuated thereby to effect closing of the upper shearingblades on their respective stringers so as to shear nails N holding theupper slats to the stringers along the entire length of the pallet. Inthis manner, all of the nails holding the upper slats in place on thepallet may be substantially simultaneously cut. Of course, after cuttingthe upper nails N, the upper shear blades are moved back to theirretracted positions. Then, hydraulic cylinder 21 is actuated so as toraise platform 13 thereby to bring lower shear blades 109 generally intothe plane of the interface between the lower slats 11 and the bottomface of stringer 10 (FIG. 12). Hydraulic cylinders 123a, 123b for thelower shear blades are then actuated thereby to cut nails N holding thelower slats onto the stringers.

In this manner it will be appreciated both the upper and lower slats canbe completely disassembled from the stringers in a relatively short timeand that the pallet need not be manually turned over to effect thecutting of the bottom slats from the stringers and that table 7 onlyneed make one cycle for completely disassembling a pallet P. Of course,it will be appreciated that this greatly increases the operating andproduction speed of the apparatus of this invention.

Referring now to FIGS. 13a, 13b and 13c, and to FIG. 14, still anotherembodiment of the nailing cutter is illustrated. In the above-noteddrawing figures, only one nailing cutter, as is generally depicted byreference character 201, is illustrated for purposes of simplicity, butit will be appreciated that three of these nails cutters 201 may beprovided on apparatus 1 in a manner similar to that as nailing cutters101A, 101B, and 101C as heretofore described. Further, in thedescription of nailing cutter 201, the "double primed" referencecharacters indicate parts of similar function and of generally the sameconstruction as parts heretofore described.

More specifically, nailing cutter 201 comprises a pair of spaced,cantilever support arms 45a", 45b" extending from a respective trolley47A, 47B or from frame 3 in the same manner as nailing cutter 101A, 101Bor 101C. Arms 45a", 45b" are, as shown in FIG. 14, of a height less thanthe height of a stringer 10 of a pallet P to be disassembled whereby thearms may be readily inserted into the pallet. The arms are spaced forreceiving a stringer 10 therebetween. Each arm carries at least oneshear blade. As shown, and is preferred in most applications, however,each arm 45a", 45b" carries a pair of shear blades including an uppershear blade 203 and a lower shear blade 205. The upper and lower shearblades of each pair of arms are selectively operable for severing nailsN holding the top slats onto the stringers or for severing the nailsholding the lower slats onto the stringer in a manner as will appear.Each shear blade 203 or 205 is somewhat longer than stringer 10 ofpallet P and has its cutting edge facing inwardly toward its respectivestringer. Further, each blade is slidably carried on its respective armfor both longitudinal movement along the length of its arm and fortransverse movement toward and away from its respective stringer. Asshown, each blade is retained in sliding relation on its arm by means ofa retainer plate 207. The ends of each of the blades are angled at, forexample, a 45° angle and constitute a front cam surface 209 and a rearcam surface 211. A cam actuator, as generally indicated at 213, isprovided for the simultaneous closing of the upper shear blades of nailcutter 201. Of course it will be appreciated that a similar cam actuator214 (see FIG. 15) is provided for actuating the lower blades. Actuator213 includes a cam member 215 movable in generally longitudinaldirection relative to its respective shear blades and to its respectivearms 45a", 45b" from a first or open position (as shown in FIG. 13a), toan intermediate position (as shown in FIG. 13b), and then to a second orclosed position (as shown in FIG. 13c) by means of a hydraulic cylinderunit 217. Cam member 215 has a V-shaped cam surface 219 cooperable withthe rear cam surfaces 211 of its respective shear blades. Arms 45a",45b" each have an angled from surface 221 cooperable with the front camsurface 209 of the shear blades. Cam rollers 223 may be disposed betweenthe cam surfaces of the blades and support arm cam surfaces thereby tofacilitate closing of the shear blades.

As shown in FIG. 14a, as hydraulic cylinder unit 217 is actuated and ascam actuator 215 is moved longitudinally toward the free ends of thesupport arms, cam surfaces 211 and 219 cooperate to cammingly move therear ends of the upper shear blades inwardly toward stringer 10positioned therebetween. Of course, it is assumed that the upper shearblades are in general heightwise alignment with the interface betweenthe upper face of stringer 10 and the bottom face of the upper or topslats 11 of the pallet P to be disassembled. In the manner, the cuttingedges of the upper shear blades enter the joint between the slats andthe stringer so as to cuttingly engage nails N.

With the upper shear blades in the position shown in FIG. 13a, the rearends of the shear blades preferably (but not necessarily) overlap withone another with one blade on top so as to form a scissors-like cuttingaction on nails N. Also, the rear ends of the shear blades come uponstops (not shown) so as to prevent excessive overlapping of the blades.

Upon continued longitudinal movement of cam member 215, the upper bladesare urged longitudinally of arms 45a", 45b" and front cam surfaces 209cammingly engage stationary front cam surfaces 221 on their respectivesupport arms. Thus, relative movement between the blades and the camscauses the front ends of the blades to close. As the blades move intocutting contact with nails N, they contact the nails from front-to-rearalong the length of stringer 10 in a scissors-like, nail shearingaction. It will thus be appreciated that with nail cutter 201 only onenail at a time is cut by the blades thus allowing a high shearing forceto be applied on each of the nails to be cut without the requirement ofhaving to apply excessively high forces to close the blades. Of course,suitable return springs 224 may be provided in cutter 201 so as toreturn the shear blades to their open position upon hydraulic cylinderunit 215 being returned to its first or open position. It will beunderstood that the bottom shear blades are constructed and operated inthe same manner as the above-described top shear blade.

After the top nails N of pallet P have been cut, as above described,table 7 is raised so that the bottom blades 205 are in alignment withthe bottom interface between stringers 10 and bottom slats 11 of thepallet. Thus, the bottom blades may be closed in the same manner asabove described so as to cut bottom nails N. It can thus be readilyappreciated that both the top and bottom nails of pallet P may be cutwithout the necessity of handling the pallet or repositioning the palletrelative to the nail cutters other than the above described heightwiseadjustment of table 7.

It will be further appreciated that if either nail cutter 101A, 101B,101C, or 201 are used, the provision of a retractable front abutmentmember 23', as shown in FIG. 16 may be preferred. Briefly, abutmentmember 23' is mounted on compression coil springs 301 which permit it tomove into a retracted position within a recess 303 provided in the frontportion of table 7 upon the raising of the table so as to effectalignment of the bottom interface between the pallet slats and thestringers with the lower shear blades of the nail cutters. It will beappreciated that as table 7 is raised, the top of abutment member 23'engages the nail cutters or their cantilevered support arms and thus isforced downwardly into its recess against the bias of springs 301. Also,prior to raising table 7, it will be appreciated that clamp member 25 ismoved to its unclamped position so that it will not interfere with thecantilever support arms for the nailing members.

From the above description of the operation of apparatus 1 with nailingcutters 9A, 9B and 9C with nailing cutters 101A, 101B and 101C, for thesake of brevity, the method of this invention is believed to beabundantly clear to one skilled in the art and thus it is not believednecessary to set the method out in detail in this specification.

Of course, it will be understood that if one is disassembling a pallet Phaving more than three stringers, either additional nail cutting means9, 101, or 201 may be provided so as to simultaneously effect thecutting of all slats from the stringers, or after cutting some of theslats from the stringers, the table 7 may be returned to its retractedposition, clamp 25 loosened, and the pallet shifted transverselyrelative to the nail cutter so as to align another of the nail cuttersup with the other stringers of the pallet. Also, for economical versionsof the present apparatus, only one of the above-described nailingcutters need be used and that the pallet being disassembled may beshifted in transverse direction so as to align its stringers with theone nailing cutter.

As shown, apparatus 1 has its rails 5 on the outside of its frame. Itwill be appreciated that the rails could be moved inboard of the frameso as to expose winch assembly 33 and hudraulic cylinders 21 and 29 formore ready servicing thereof.

In this disclosure, the term "shear" is used in a generic sense to referto any cutting or breaking action of nails N holding the slats to thestringers of a pallet.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

I claim:
 1. In apparatus for unnailing wood structures, said apparatusincluding a frame, nail cutting means, an elongate support for said nailcutting means mounted at one end of said frame, a support for a pallet,means for causing relative movement of said pallet and said nail cuttingmeans to effect cutting of the nails by the relative movement betweenthe pallet and the nail butting means, said nail cutter supportcomprising a pair of side-by-side horizontal cantilever arms, and nailcutting means comprising a pair of rotary circular blades carried bysaid arms, one blade on each arm, wherein the improvement comprises:means for journalling said each of said circular blades on itsrespective arm comprising a stud secured to said arm, and anti-frictionbearing having an inner race and an outer race, said inner race beingadapted to receive said stud, an outer mounting member surrounding saidstud and having a bore therein for reception of said outer race of saidbearing, said blade being secured to said mounting member whereby saidblade is free to rotate about said stud and is securely held in positionon said stud, said bearing means further comprising means for adjustingthe side-to-side position of said pair of blades relative to one anotherand for selectively locking each of said blades in any desired positionrelative to one another and relative to its respective support arms,this last-said means comprising a mounting plate carrying one of saidblades, a pivot connection between said mounting plate in its respectivearm, a pin and slot connection between said mounting plate and itsrespective arm so as to permit adjustable pivoting movement about saidpilot connection of said mounting plate relative to its said arm, and aneccentric cam between said mounting plate and said arm for adjustablymoving said mounting plate relative to said arm within a selected rangeof pivotal positions whereby with said pin and slot and said pivotconnections being tightened and with said cam engaging said mountingplate and arm, the mounting is held against movement relative to itsrespective arm.
 2. Apparatus for disassembling wood pallets or the like,said pallets comprising a nailed together wood structure having aplurality of spaced stringers and a plurality of slats nailed to thestringers and extending transversely thereof, said apparatuscomprising:a frame; means mounted on said frame for reciving a pallet tobe disassembled; a plurality of nail cutting means, one for a respectivestringer, said nail cutting means being adapted to cut the nails holdingthe slats to a respective stringer; means for effecting relativemovement of said pallet receiving means with said pallet thereon andsaid nail cutting means; means for holding said pallet on said palletreceiving means in position with its stringers extending parallel to thedirection of movement of said pallet receiving means; and means foradjustably moving in transverse direction at least some of said nailcutting means so as to align certain of said nail cutting means with arespective stringer of said pallet, each of said nail cutting meansbeing supported on an elongate, cantilever support, and each of saidadjustably movable nail cutting means including means for self-centeringsaid adjustably movable nail cutting means relative to its respectivestringer upon effecting cutting of said nails.
 3. Apparatus as set forthin claim 2 wherein each of said elongate cantilever arms for each ofsaid adjustably movable nail cutting means is mounted on a track carriedby said frame for movement thereof in a direction generally transverseto the direction of movement of said table.
 4. Apparatus as set forth inclaim 3 further comprising power operated means for effecting selectedtransverse movement of said movable nail cutting means, this last-saidpower operated means also constituting said self-centering means bypermitting said nail cutting means to move substantially freely on saidtrack upon effecting cutting of said nails thereby to effectself-centering of the nail cutting means with respect to its respectivestringer.
 5. Apparatus as set forth in claim 4 wherein said poweroperated means comprises a hydraulic cylinder unit interconnecting saidmovable nail cutting means and said frame for effecting said transversemovement of the former, said cylinder unit being open when said nailcutting means is in approximate alignment with its respective stringerand thus being substantially free to move in transverse directionrelative to its respective stringer so as to permit self-centering ofthe nail cutting means on its respective stringer upon effecting cuttingof the nails.
 6. Apparatus as set forth in claim 2 wherein said palletreceiving means includes a table having a platform and a carriage, saidplatform being supported on said carriage and the latter being movablealong the frame between said retracted position and said operativeposition, said carriage including means for selectively raising andlowering said platform relative to said carriage and relative to saidnail cutting means whereby the interface between said stringer and saidslats of a pallet supported on said table may be selectively adjusted inheight-wise relation relative to said nail cutting means.
 7. Apparatusas set forth in claim 6 wherein said platform height adjustment meanscomprises a parallelogram linkage arrangement interconnecting saidplatform in said carriage and power operated means for effecting raisingor lowering of said platform relative to said carriage.
 8. Apparatus asset forth in claim 2 wherein said pallet holding means comprises a fixedabutment engageable with the leading end of a pallet to be clamped onsaid pallet receiving means and a clamping jaw having another abutmentmember thereon movable between an open position and a closed position inwhich said clamping jaw clampingly engages said pallet between saidabutment members and holds it against movement as said table moves fromits retracted to its operative position.
 9. Apparatus as set forth inclaim 2 wherein said pallet receiving means comprises a table havingpower operated means for effecting movement of said table between itsretracted and operative positions, said power operated means comprisinga winch secured to said frame, a pulley secured to said frame distal tosaid winch, said winch and pulley being separated by a distance greaterthan or equal to the travel to said table as it moves from its retractedposition to its full operative position, and a cable operatively woundon said winch and entrained around said pulley so that upon driving saidwinch in one direction, said table is moved longitudinally of said framefrom its retracted to its operative position and upon driving said winchin opposite direction said table is returned to its retracted position.10. Apparatus as set forth in claim 3 wherein each of said elongatesupports comprises a pair of parallel arms spaced apart so as toaccommodate a stringer therebetween.
 11. Apparatus as set forth in claim10 wherein each of said nail cutting means comprises a pair of knives,one carried on the outer end of each of said arms, said knives being atleast partially overlapping so that upon engaging nails fastening theslats to a respective stringer of said pallet, said knives cut saidnails as the pallet moves relative to the knives toward its operativeposition.
 12. Apparatus as set forth in claim 11 comprising guidescarried by the outer or free end of each of said arms for guiding arespective stringer toward said knives.
 13. Apparatus as set forth inclaim 11 wherein each of said knives is a rotary circular blade, andwherein said apparatus comprises means for journalling said each of saidcircular blades on its respective arm comprising a stud secured to saidarm, and anti-friction bearing having an inner race and an outer race,said inner race being adapted to receive said stud, an outer mountingmember surrounding said stud and having a bore therein for reception ofsaid outer race of said bearing, said blade being secured to saidmounting member whereby said blade is free to rotate about said stud andis securely held in position on said stud.
 14. Apparatus as set forth inclaim 11 further comprising means for adjusting the side-to-sideposition of said pair of knives relative to one another and forselectively locking each of said knives in any desired position relativeto one another and relative to its respective support arms, thislast-said means comprising a mounting plate carrying one of said knives,a pivot connection between said mounting plate in its respective arm, apin and slot connection between said mounting plate in its respectivearm so as to permit adjustable pivoting movement about said pivotconnection of said mounting plate relative to its said arm, and aneccentric cam engageable with said mounting arm at any point wherein aselected range of pivotal positions whereby with said pin and slot andsaid pivot connections being tightened and with said cam engaging saidmounting plate, the latter is held against movement relative to itsrespective arm.
 15. Apparatus as set forth in claim 2 wherein each ofsaid cutting means comprises a pair of opposed shear blades with oneshear blade on each side of a respective stringer of a pallet to bedisassembled, and means for selectively closing said blades on itsrespective stringer thereby to cut the nails holding the slats on oneface of said respective stringer.
 16. Apparatus as set forth in claim 15wherein each said pair of shear blades is supported by a respective pairof cantilevered arms, each of said arms carrying a respective shearblade, said arms being spaced apart a distance so as to receive one ofsaid pallet stringers therebetween.
 17. Apparatus as set forth in claim16 wherein each of said arms carries power actuated means for effectingmovement of its respective blade from a retracted position clear of astringer disposed between said blades inwardly toward this last-saidstringer so as to cooperate with the other of said blades thereby to cutsaid nails, said blade then being movable in opposite direction awayfrom said stringer toward its retracted position.
 18. Apparatus as setforth in claim 17 wherein each of said arms includes a slide support forslidably receiving one of said blades, said slide support having a camsurface cooperable with its respective blade for forcing its respectiveblade inwardly toward its respective stringer upon longitudinal movementof said blade in one direction relative to said arm and for permittingoutward movement of said blade upon longitudinal movement of the bladein the other longitudinal direction.
 19. Apparatus as set forth in claim18 wherein said power actuated means for each of said blades comprises ahydraulic cylinder unit carried by its respective arm and coupled tosaid blade and said arm for shifting said blade longitudinally relativeto said arm.
 20. Apparatus as set forth in claim 17 wherein each of saidarms carries two of said blades, an upper blade and a lower blade, saidupper and lower blades being spaced from one another a distance lessthan the height of a stringer of a pallet to be disassembled, and poweroperated means actuable independently of one another for effectingmovement of a selected upper or lower blade from its retracted positiontoward its stringer or for retracting this selected blade, saidapparatus further including selectively operable means for effectingrelative height adjustment between said pallet and said nail cuttingmeans thereby to substantially align the upper blades of said nailcutting means with the interface between the upper slats and saidstringers so as to effect the cutting of said nails securing the upperslats to the stringers upon actuation of said upper shear blades and tosubstantially align the lower blades of each of said nail cutting meanswith the interface between the lower slats in said stringers so as toeffect the cutting of said nails securing the lower slats to thestringers upon actuation of said lower shear blades.
 21. Apparatus asset forth in claim 20 wherein each of said arms includes a slide supportfor its respective upper and lower blades, said slide support having anupper cam surface for said upper blade and a lower cam surface for saidlower blade for forcing said blades inwardly toward said stringer uponselected longitudinal movement of said upper or lower blades. 22.Apparatus as set forth in claim 21 wherein said powered actuated meanscomprises an upper hydraulic cylinder coupled between said arm and saidupper blade for effecting longitudinal movement of said upper blade, anda lower hydraulic cylinder unit coupled between said arm and said lowerblade for effecting longitudinal movement of said lower blade. 23.Apparatus as set forth in claim 18 wherein said cam surface for one ofsaid blades of a pair of opposed shear blades forces said one bladeinwardly into cutting engagement with said nails upon movement of saidone blade in one longitudinal direction with respect to its respectivesupport arm, and wherein said cam surface for the other blade of saidpair of blades forces said other blade inwardly into cutting engagementwith said nails upon movement of said second blade in oppositelongitudinal direction with respect to its arm.
 24. Apparatus fordisassembling nailed together wood structures, such as wood pallets orthe like, said wood structures having a plurality of generally parallelstringers extending longitudinally of the wood structure and beingspaced from one another, and a plurality of slats extending transverselyof the stringers and being nailed to the outer faces thereof, saidapparatus comprising:a frame; means for receiving a wood structure to bedisassembled, said means being movable relative to said frame between aloading position in which a wood structure may be placed thereon and anoperative position in which the nails holding the slats of the wood ofthe stringers are to be cut; a plurality of nail cutting means operablewhen said means with a wood structure thereon is in its operativeposition so as to cut the nails holding the slats to a stringer adjacentthe cutting means; and means for adjustably moving at least certain ofsaid nail cutting means transversely relative to the pallet positionedon said means so as to align said certain nail cutting means with theirrespective stringers, said adjustably movable nail cutting means eachincluding means for self-centering the latter relative to its respectivestringer upon effecting cutting of the nails holding said slats to itsrespective stringer.
 25. Apparatus as set forth in claim 24 wherein eachof said cutting means comprises a pair of opposed shear blades with saidshear blades disposed on opposite sides of a respective stringer whensaid pallet and said table are in their operative positions, and meansfor selectively closing said blades on its stringer comprising cam meansat the front and rear ends of each of said blades and cam actuator meansfor cammingly engaging said front and rear cam surfaces on said bladesso as to close said blades in such manner that said blades cut saidnails one at a time.
 26. Apparatus as set forth in claim 24 wherein eachof said nail cutting means is supported on an elongate cantileveredsupport.
 27. Apparatus as set forth in claim 25 wherein said nailcutting means further comprises a pair of side-by-side support arms,each of said arms slidably carrying one of said pair of blades, each ofsaid arms having a front cam interface cammingly engageable with saidfront cam surface of its respective blade.
 28. Apparatus as set forth inclaim 26 wherein each of said elongate cantilever arms for each of saidadjustably movable nail cutting means is mounted on a track carried bysaid frame for movement thereof in a direction transverse to said palletpositioned on said means.
 29. Apparatus as set forth in claim 28 furthercomprising power operated means for effecting selected transversemovement of said movable nail cutting means and for permitting said nailcutting means to move substantially freely on said track upon effectingcutting of said nails thereby to self-center the nail cutting means withrespect to its respective stringer.
 30. Apparatus as set forth in claim29 wherein said power operated means comprises a hydraulic cylinder unitinterconnecting a respective movable nail cutting means and said framefor effecting said transverse movement of the former, said cylinderunit, when said nail cutting means is in approximate alignment with itsrespective stringer, being open so as to permit self-centering of thenail cutting means on its respective stringer upon effecting cutting ofthe nails.
 31. Apparatus as set forth in claim 24 wherein said means isa table includes a platform and a carriage, said platform beingsupported on said carriage and the latter being movable longitudinallyof the frame between said retracted position and said operativeposition, said carriage including means for selectively raising andlowering said platform in relation to said carriage relative to saidnail cutting means whereby the interface between said stringer and saidslats may be selectively adjusted in height-wise relation relative tosaid nail cutting means.
 32. Apparatus as set forth in claim 31 whereinsaid platform height adjustment means comprises a parallelogram linkagearrangement interconnecting said platform and said carriage, and poweroperated means for effecting raising or lowering of said platformrelative to said carriage.
 33. Apparatus as set forth in claim 24wherein each of said cutting means comprises a pair of opposed shearblades with the shear blades disposed on opposite sides of a respectivestringer when said pallet and said table are in their operativepositions, and means for selectively closing said blades on itsrespective stringer thereby to cut said nails.
 34. Apparatus as setforth in claim 33 wherein said pair of shear blades is supported by apair of cantilevered arms, each of said arms carrying a respective shearblade, said arms being spaced apart a distance so as to receive arespective pallet stringers therebetween.
 35. Apparatus as set forth inclaim 34 wherein each of said arms carries power actuated means foreffecting movement of its respective blade from a retracted positionclear of a stringer disposed between said blades inwardly toward thislast-said stringer for cooperating with the other of said blades therebyto cut said nails, said blade then being movable in opposite directionaway from said stringer toward its retracted position.
 36. Apparatus asset forth in claim 35 wherein each of said arms includes a slide supportfor slidably receiving one of said blades, said slide support having acam surface for forcing its respective blade inwardly toward itsrespective stringer upon longitudinal movement of said slide in onedirection relative to said arm and for permitting outward movement ofsaid blade upon movement of the blade in the other longitudinaldirection.
 37. Apparatus as set forth in claim 35 wherein said poweractuated means for each of said blades comprises a hydraulic cylinderunit carried by its respective arm and coupled to said blade forshifting the blade longitudinally relative to said arms.
 38. Apparatusas set forth in claim 34 wherein each of said arms carries two of saidblades, an upper blade and a lower blade, said upper and lower bladesbeing spaced from one another a distance less than the height of astringer of a pallet to be disassembled, and power operated meansactuable independently of one another for effecting movement of saidselected blade from its retracted position toward its stringer or forretracting said blade, said apparatus further including selectivelyoperable means for effecting height adjustment between said pallet andsaid nail cutting means thereby to substantially align the upper bladesof said nail cutting means with the interface between the upper palletsslats and said stringers so as to effect the cutting of said nailssecuring the upper slats to the stringers and to substantially align thelower blades of each of said nail cutting means with the interfacebetween the lower pallet slats in said stringers so as to effect thecutting of said nails securing the lower slats to the stringers. 39.Apparatus as set forth in claim 38 wherein each of said arms includes aslide support for its respective upper and lower blades, said slidesupport having an upper cam surface for said upper blade and a lower camsurface for said lower blade for forcing said blades inwardly towardsaid stringer upon selected longitudinal movement of said upper or lowerblades.
 40. Apparatus as set forth in claim 39 wherein said poweredactuated means comprises an upper hydraulic cylinder coupled betweensaid arm and said upper blade for effecting longitudinal movement ofsaid upper blade, and a lower hydraulic cylinder unit coupled betweensaid arm and said lower blade for effecting longitudinal movement ofsaid lower blade.
 41. Apparatus as set forth in claim 39 wherein saidslide support cam surface for one of said blades of a pair of bladesforces said one blade inwardly into cutting engagement with said nailsupon movement of said one blade in one longitudinal direction withrespect to its respective support arm, and wherein said cam surface forthe other blade of said pair of blades forces said other blade inwardlyinto cutting engagement with said nails upon movement of said secondblade in opposite longitudinal direction with respect to its arm. 42.Apparatus as set forth in claim 27 wherein said cam actuator meansincludes a cam member cammingly engageable with said rear cam surfaceson said blades and power actuated means for forceably moving said cammember generally longitudinally of said arms for closing said blades.